Sadly, some people in this world are not honest. In an increasingly wired world, dishonest people have found myriad opportunities to snoop or otherwise illicitly acquire one's personal or confidential data, such as to monitor one's activities on a network, e.g., to monitor what you are doing, downloading, watching, accessing, etc., to monitor your telephony (e.g., VoIP and equivalents) control and voice data, to monitor and/or interfere with protocols on your network, such as to interfere with SNMP (Simple Network Management Protocol) commands, RTP (Real Time Transport Protocol) data, etc.
To address risk of another's dishonesty, typically secured communication protocols, such as SSL (Secured Socket Layer), TLS (Transport Layer Security), and the like are utilized to protect one communication of one's data. For more information regarding TLS, see, for example, Internet RFCs (Request for Comments) 2246 (The TLS Protocol Version 1.0), 2712 (Addition of Kerberos Cipher Suites to TLS), 2817 (Upgrading to TLS Within HTTP/1.1), 2818 (HTTP Over TLS), 3268 (AES Ciphersuites for TLS), 3546 (TLS Extensions), and 3749 (Protocol Compression Methods). Please note, all RFCs cited herein are available at Internet URL www:ietf:org/rfc. See also the GNU TLS Library [Overview] at URL www:gnu:org/software/gnutls. (Note, to prevent inadvertent hyperlinks, periods in URLs cited herein have been replaced with colons.)
Unfortunately, TLS, SSL, and many other security environments expect an underlying communication protocol to be TCP/IP (Transport Control Protocol/Internet Protocol). Unfortunately, some protocols and application programs, such as VoIP, RTP, SNMP, etc. only operate on an unreliable communication transport such as UDP (User Datagram Protocol) that is not supported by TLS, SSL, and the like. There have been attempts to provide security over unreliable transports such as UDP, for example, the IPSec (IP Security) protocol or SNMPv3 which provides protocol specific security. For more information regarding IPSec, see related RFCs available at www:ietf:org/html:charters/ipsec-charter:html. Unfortunately, these solution attempts suffer from overhead, complexity, as well as protocol-specific limitations, such as having to rewrite a protocol such as SNMP (Simple Network Management Protocol) into SNMP v3 in order to use the security features. Other limitations include, for example, interoperability and deployment issues because of using proprietary, non-standard security solutions for these protocols.